Research On The Anti-reflection Characteristics Of Supercritical CO₂ Gas Explosion In Low-permeability Coal

Supercritical CO2 gas explosion enhancement of low permeability coal is a new type of coal seam penetration enhancement method,which has the advantages of safety and energy saving,environmental protection,easy operation,low cost,etc.,to study the influence factors of supercritical CO2 gas explosion on the enhancement effect of coal.It is of great significance.In this paper,on-site gas explosion tests,theoretical and numerical simulations are carried out for supercritical CO2 gas explosion to increase the permeability of low-permeability coal.According to the experimental coal seam conditions in Yangquan mining area,the existing cracker structure has been optimized and improved.The gas content,initial speed of dispersing,and the amount of drill cuttings of the coal before and after the blasting of the experimental working face of the 15 th coal seam are measured and analyzed in the laboratory and on-site.It is concluded that the supercritical carbon dioxide gas explosion test has a positive effect on the release of gas in the coal body,and the development of cracks in the coal body can reduce the media stress,and the effect of increasing the permeability of the low-permeability coal seam is obvious.Through the investigation of the gas concentration and scalar in the observation hole of the drainage observation hole before and after the blasting in the belt lane of the 15303 working face in the third mining area of the experimental working face,it can be known that the use of liquid carbon dioxide photos and other technologies in the mining process of the coal mine can be fully improved Its thickening effect.Moreover,according to a large number of field tracking tests,it can be found that the effective influence radius of the new large explosion pressure fracturing device on coal seam fracturing has been increased to more than 2.5m,and the coal permeability has increased by 10.85?12.20 times.This article theoretically analyzes the energy equivalent of supercritical CO2 gas explosion antireflection based on knowledge of porous media,elastoplastic mechanics,fracture mechanics and heat.The results show that the higher the pressure of the cracker cavity,the greater the TNT equivalent of the gas explosion energy.Assuming that the entropy invariant condition is satisfied,the relationship between the TNT equivalent and the indoor pressure is a non-linear growth state,while the assumed isothermal environment will explode.The energy TNT equivalent has a positive linear relationship with the pressure in the cavity.However,the initial states of the two are the same,and the TNT equivalent value is higher in an isothermal environment than in an isentropic environment;it is theoretically analyzed why supercritical CO2 can increase penetration,and the impact process of supercritical carbon dioxide on coal is described in detail,revealing The law and nature of the propagation and exhaustion of the gas blast waveAfter simulation with FLAC3 D finite difference software,simplification was carried out.After the simulation calculation of the supercritical carbon dioxide phase change gas explosion stress attenuation law was carried out specifically for coal seam pre-fracture,coal body strength,and other main control factors,the coal seam carbon dioxide phase The stress attenuation law of variable gas explosion is analyzed from two perspectives: qualitative and quantitative.Through simulation calculation,it can be found that with the gradual increase of the pre-fracture length,the remaining gas explosion fracturing influence range shows a linear increase relationship.It can also be seen that the gas explosion fracturing enhancement range will be affected by the pre-fracture.The obvious influence of the length;there is a correlation between the gas pressure and the influence radius of the gas burst cracking,the most important reason is that the effective stress of the coal body gradually decreases due to the existence of the gas pressure,and the coal body actually needs to be in the process of crack propagation The overcoming stress will show a gradual decrease trend.In this case,the actual range of influence will also increase.In this case,it can be seen that the gas explosion crack propagation process will be affected by each layer of gas to a certain extent.The promotion of stress.The paper has 43 pictures,5 tables,and 94 references.